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Step
1 Use the appropriate formula
to calculate the pressure of each gas, as if it was on its own, in the 60L
vessel.
Step 2 Add
up the individual pressures of each gas
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P_{1}V_{1} = P_{2}V_{2 }_{Continue with assistance.}_{ }
P_{1}V_{1} = P_{2}V_{2}
For oxygen
P_{1} = 120 kPa, V_{1} = 25L, P_{2} = ?, V2 = 60L,
P_{2} = (120 X 25)/60 = 50 kPa.
For gas nitrogen
P_{1} = 200 kPa, V_{1} = 25L, P_{2} = ?, V2 = 60L,
P_{2} = (200 X 25)/600 = 83.3 kPa.
Hide the solution
Since the temperature, pressure and volume of each gas changes but the amount remains fixed, use the formula below.
and tranform to make it equal
to P_{2}
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Calculating the partial pressure of oxygen where
P_{1} =230 kPa
V_{1} = 40L
T_{1} = (20 + 273) = 293K
T_{2} = (100 + 273) =373K
V_{2} = 100L
P_{2} = 230 X 40 X 373/(293 X 100) = 117.12 kPa
Calculating the partial pressure of hydrogen where
P_{1} =100 kPa
V_{1} = 60L
T_{1} = (20 + 273) = 293K
T_{2} = (100 + 273) =373K
V_{2} = 100L
P_{2} = 100 X 60 X 373/(293 X 100) = 76 38 kPa
Partial pressure (Dalton's Law)



Two containers are connected by a stopcock as shown on the left. Gas "A" is at a pressure of 202 kPa while gas "B" is at a pressure of 140 kPa. What will the resultant pressure be when the stopcock is opened? Step 1 Calculate the pressure
that each gas alone will exert when the stopcock is opened. P_{1}V_{1} = P_{2}V_{2}

Two containers
are connected by a stopcock as shown on the right. Gas "A" is
at a pressure of 402 kPa while gas "B" is at a pressure of 100
kPa. What will the resultant pressure be when the stopcock is opened?


25 litres of oxygen gas at 120kPa and 25 litres of nitrogen gas at 200 kPa are pumped into an evacuated(empty) 60 litre vessel. What is the final pressure of the 60 litre vessel if the temperature remained constant? Clues 

An 60 litre metal vessel contains carbon dioxide at 160 kPa and 23^{o}C. A further 300 litres of nitrogen gas are pumped into this vessel at 140 kPa and 23^{o}C. If the volume of the vessel and temperature remain constant what is the final pressure of the vessel?


A vessel containing 60L of
hydrogen gas at 20^{o}C and 100kPa pressure is connected via a
valve to a 40L vessel containing oxygen at 20^{o}C and 230kPa
pressure. The valve is opened and both gases expand to fill the entire
volume of both vessels. Answer 